#no mpls ip propagate-ttl cmd question-?

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Jun 13th, 2007
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Hi:


When this cmd. is enabled both on PE1 and PE2 across a MPLS core, why does the trace output show the egress PE2 router in the output?


I have CE1->PE1->P->PE2->CE2.


I am tracing to the lo0 of CE2 10.1.8.8


PE1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

PE1(config)#no mpls ip propagate-ttl

PE1(config)#end


PE2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

PE2(config)#no mpls ip propagate-ttl

PE2(config)#end


CE1#tr ip 10.1.8.8


Type escape sequence to abort.

Tracing the route to 10.1.8.8


1 10.1.17.1 28 msec 28 msec 28 msec

2 10.1.58.5 168 msec 180 msec 168 msec

3 10.1.58.8 112 msec * 112 msec

CE1#


As you can see, 10.1.58.5 is the PE2 intf. to CE2. I was hoping to see only 2 hops.


Now the doc for this cmd does say that it sometimes shows the egress provider router.


Is this based on IOS or router model?

Or just another bug ;->


Thx.


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Harold Ritter Wed, 06/13/2007 - 10:08
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  • Cisco Employee,

Niraj,


This is normal behavior. This command will hide the SP core except for the ingress and egress PE.


Hope this helps,

rajju Wed, 06/13/2007 - 15:21
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Thanks Harold!!


I was going by the example shown in the pdf for MPLS Technology Essentials where they only showed 2 hops, the 1st PE and then CE2 and thus....(they did state that sometimes the egress PE would also show up)....



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